Glossary » legacy system
an old hardware or software system which is generally out-dated in some way, either based on obsolete hardware or using an older user interface (such as a character-based interface). The term is usually used when planning a new system to replace or extend the legacy system.
For legacy systems, two issues generally concern user interface designers. First, will a new system really provide a better user interface than the legacy system? That is, switching from a character-based interface to a graphical user interface will rarely improve the usability of dedicated software without also doing task analysis and user testing to ensure improvement. Second, how will users’ experience with the legacy system affect their training time to learn the new system? What degree of similarity to the legacy user interface is appropriate in the newly-designed interface?